A 17-year-old girl presented with migraine with prolonged aura and aura without headache. Neurologic examination was normal. Her mother, who did not have a history of migraine, developed right-face and -arm numbness at the age of 45. Evaluation revealed white matter changes consistent with CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and genetic testing showed a Notch3 gene mutation consistent with CADASIL. Our patient's MRI revealed white matter changes and the same Notch3 gene mutation. Low-dose aspirin was started in an attempt to prevent stroke. CADASIL is considered a degenerative disease of adult onset that leads to progressive neurologic deterioration. Onset of symptoms is in the third decade. Migraine, one of its most common manifestations, can develop in childhood. Evaluation for secondary causes is warranted in select pediatric patients who present with atypical migraine, when there is a family history of CADASIL or atypical patterns such as aura without headache, or in the presence of white matter abnormalities. The pathophysiology of CADASIL is poorly understood, and there is no proven effective therapy. Patients require genetic counseling and close follow-up. It is not known if interventions such as antiplatelet therapy are beneficial if instituted early in the course of the disease. Screening of family members at risk for CADASIL, even in the pediatric population, should be considered and offered to patients with CADASIL and their families. CADASIL has rarely been described in the pediatric population. This case report expands our current understanding of the disorder in children.